Do you know bookmarking submission content rules.??

Hello guys.
Do you know about bookmarking submission content rules.?
Like how many characters & words use in bookmarking content and Title.??
What content should be.??
I mean quality of content rules. Like what type of word use or not, keyword density and more Information about that..
Let me know if you know this, please..

Generally people use the targeted keyword in the title of bookmark and use details similar to directory submission details (around 250 characters) and make an informative description which includes targeted keywords.

Generally people use the targeted keyword in the title of bookmark and use details similar to directory submission details (around 250 characters) and make an informative description which includes targeted keywords.

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thanks..
but can you tell me about which type of content very effctive.
some time content errors are often do you know why.???